Manufacture of artificial silk from viscose



Patented Apr. I 13 1926.

UNITED sTaTEs WILLIAM MENDEL, on

1,580,844 PATENT OFFICE.

BEVERLY, NEW JERSEY, ASSIGNOR TO SAME'EL A. NEIDICH, F EDGEWATER PARK,NEW JERSEY.

MANUFACTURE OF ARTIFICIAL SILK FROM VISCOSE.

Io Drawing.

To all whom it may concern:

Be it known that 1, WILLIAM MENDEL, a citizen of the United States,residing at Beverly, in the county of Burlington anda State of NewJersey, have invented a certain new and useful Improvement in theManufacture of Artificial Silk from Viscose, whereof the following is aspecification.

My invention relates to the manufacture of filaments by projectingviscose (variously known as cellulose sulphocarbonate or cellulosethiocarbonate) through minute spinne'ret orifices into baths containingchemicals which coagulate the viscose as a scmi'solid impure cellulosehydrate, which must be subjected to subsequent cleaning processes andthereafter dried .to form the commercial artificial silk.

Natural silk filaments have an average diameter of .015 millimeter and,therefore, it is highly desirable to produce artificial silk filamentsof approximately themsame diameter. However, the aforesaid coagulatedviscose elements must, of course, be of sufficient strength to withstandthe stresses of manipulation incident to their production,-and' as theviscose products of ordinary proccsses are. much weaker and morefrangible than the natural silk filaments it has been found impossibleto commercially manufacture viscose silk filaments which are less thandouble the diameter of the natural silk filaments. For instance, if

. dried in air, the minimum diameter of ordinary viscose silk filamentsis .03051 millimeter and if viscose silk filaments are sub jected to theaction of glycerine, as is usual to improve their. flexibility, theminimum ultimate diameter attainable is .03545 milli-' 40 meter.

Therefore, an object and elfect of my in-' ca se of their prompt actionand relatively lo v cost, strong acid baths, such as aqueous solutionscontaining eight per cent of sulphuric acid of five per cent ofhydrochloric acid are commonly used. With baths of that character,substantially all of the sulphur primarily chemically combined with thecellulose in viscose is released as free Application filed May 28, 1925.Serial .No. 33,503..

sulphur, but is occluded in the mass of cellulose hydrate, causing thelatter to present an undesirable dull yellow white appearance,

whereas, natural silk has a characteristic lustrous, translucentappearance. Therefore, such ordinary processes of coagulation must besupplemented by successive treatments of the coagulated viscose in:chemical baths with a view to removal of the sulphur impuritiestherefrom. However, although such cleansing operations are onlypartially plusion and occlusion of sulphurderivatives 1n the cellulosehydrate and subsequent partial elimination of the. same, leaving thecellulose hydrate of spongy texture.

Therefore, an object and-'effect of my invention is to provide a methodand means for commercially producing viscose silk filaments-without.occluding free '.sulpl1ur or its derivatives therein and to thusavoidresult which permits the formation of fila- I ments, in accordancewith this invention, as fine as natural silk filaments.

I have discovered that the desirable results aforesaid are attainable bysubjecting viscose. to the action of P0 ions. Such ions have abeneficial effect if added to or formed in the viscose, or in any bathin which viscose may be coagulated, or in a fluid distinct from eitherthe viscose or the coagulating medium and, in the latter case, may beeither alone or in association with other matter aflecting the viscosecomplex. For'instauce, the impure cellulose hydrate product ofcoagulation of viscose. may be subjected to PO, ions in a fluidcontaining dyeing material or .detergent material.

PO ions have the apparent eifect, of preventing the formation of sulphuror its derivatives in insoluble form, and thus render the coagulatedproducts practically self-cleansing. However, if PO ions be added to orformed in the viscose before coagulating the same in the form offilaments, they have the effect of accelerating the progressive aging ofthe viscose which is manifested by progressive increment in viscosity ofthe viscose which may or may not be desirable in accordance with theprocess of coagulation to which the viscose is to be subjected. However,in the form of my invention herein contemplated, I prefer to subject theviscose to the action of P0 ions in a bath in which the viscose iscoagulated in the form of filaments; so that the aforesaid aging effectof the P0 ions upon the uncoagulated mass of viscose is avoided, but theviscose filament is beneficially affected by the P0 ions immediatelyupon introduction to the bath, and thus immediately strengthened towithstand the stresses to which it is subjected, in its progressionthrough and from the bath.

Such PO, ions may be added to or produced in such coagulating baths inany convenient form or manner. However, trisodium phosphate (Na PO is acheap vehicle for such ions and is further preferable because it may beconveniently used in aqueous solution.

Although an aqueous solution of either mono-sodium phosphate ordi-sodium phos phate, or said tri-sodium phosphate alone will .eifectcoagulation of viscose projected therein, particularly if the viscose isof low alkalinity and such,solution be hot; even a small ercentage,approximating a mere trace of the ion P0 is sufficient in association orconjunction with any other suitable coagulating material. The beneficialeffect of employing even a minute quantity thereof is so great as towarrant the inference that its effect is what is termed catalytic Forinstance, an aqueous bath containin 10 per cent of sulphuric acid, (H SOand containing 10 per cent'of sodium sulphate (Na SO is an ordinarycoagulating bath which is subject to the objections aforesaid, but Ifind that the addition'of even a fraction of 1 per cent of PO, to suchbath has the advantageous results above contemplated, in the eliminationof, or prevention of formation of, insoluble sulphur derivatives in orupon the filaments projected therein.

However, I prefer to use an aqueous solution containing sodiumbi-sulphite (NaHSO and salammoniac (ammon1um chloride NH,Cl), forinstance, containing twenty-five per cent of theformer and ten percentof the latter. Such a bath promptly coagulates the viscose to an impurecellulose hydrate complex sufiiciently coherent to be mechanically drawnthrough and from such found, in some instances, even after prolonged useof such a bath for the coagulating operation above contemplated, the,bath contains substantially the amount of PO, ions originally introducedtherein and, as above noted, even a fraction of one per cent issufficient for the purpose herein contemplated.

Filaments thus coagulated in accordancewith my invention may require nosubsequent treatment other than rinsing with water, as they arepractically self-cleansing, in such coagulating bath, and emergetherefromof substantially uniform homogeneous structure'and with smoothsurfaces. When such filaments are dried, preferably under tension, theyhave unusually high luster,

strength and elasticity, and filaments even finer than natural silk maybe thus produced.

Therefore, I do not desire to limit myself to the precise details ofstructure, arrangement or precedure herein set forth, as it is obviousthat various modifications may be made therein without departing fromthe essential features of my invention, as defined in the appendedclaims.

I claim:

1. The method of manufacturing artificial silk filaments from viscosewhich consists in coagulating viscose by projecting a fine filamentthereof into an aqueous solution-containing PO, ions.

2. The method of manufacturingarti'ficial silk filaments from viscosewhich consists in I coagulating viscose by projecting a fine filamentthereof into an' aqueous solution conta1n1ng PO ions associated withother ions capable of efiecting such coagulation andinsilk filamentsfrom viscose which consists in 6. The method of manufacturing artificialsilk filaments from viscose which consists in coagulating viscose byprojecting a fine filament thereof into an aqueous solution containingPO ions, resultant from inclusion of tri-sodium phosphate (Na PoQ insuch solution, with another solute capable of effecting suchcoagulation.

7. The method of manufacturing artificial silk filaments from viscosewhich consists in coagulating viscose by projecting a fine filamentthereof into an aqueous solution contaming PO ions, resultant frominclusion of 'tri-sodium phosphate (Na PO,) in such solution, withanother solute capable of effecting such coagulation.

8. Themethod of manufacturing artificial silk filaments from viscosewhich consists in coagulating viscose by projecting a fine filamentthereof into an aqueous solution con taining PO; ions, resultant frominclusion of tri-sodium phosphate (Na PO,,) in such derivatives.

solution, with anotherj' solute capable of effecting such coagulation inassociation with a third solute capable of effecting such coagulation;

9. The method of manufacturing artificial silk from viscose whichconsists in projectiii-g; filaments of the latter into an aqueoussolution in which tri-sodium phosphate (Na PO,) has been dissolved, withantacid solute capable of effecting such coagulation.

10. The step in the manufacture of artificial silk which consistsinprojecting a .filament of viscose (thiocarbonate) through an orificeless than .025 millimeter in diameter, into an aqueous bath containingP0,,ions and capable of coagulating cellulose hydrate from Viscose withrelease of soluble sulphur 11. The step in the manufacture of artificialsilk which consists in projecting a fila-' ment of viscose(thiocarbonate) through an orifice less than .025 millimeter indiameter, into an aqueous bath containing PO ions and capable ofcongulating cellulose hydrate from viscose with release of solublesulphur vderivatives; such solution being, resultant from mixture ofwater with'an inorganic acid and tri-sodium phosphate (Na PO,).

, In testimony whereof, I have hereunto signed niy name at Burlington,New Jersey, this 20th day of May, 1925. 7

WILLIAM MENDEL.

